Table 1.

Predicted deformities and the ideal location(s) and number of blocking screws while lengthening the femur and tibia using internal lengthening nail with osteotomies at different locations

Osteotomy site	Nailing technique	Predicted deformity	Blocking screw(s) in each bone fragment near the osteotomy
Proximal Femur	Antegrade	Varus	2 Medial screws
		Valgus	2 Lateral screws
		Procurvatum	1–2 Posterior screw(s)
Mid Femur	Antegrade or retrograde	Varus	2 Medial screws
		Valgus	2 Lateral screws
		Procurvatum	1–2 Posterior screw(s)
Distal Femur	Retrograde	Varus	2 Medial screws
		Valgus	2 Lateral screws
		Procurvatum	1–2 Posterior screw(s)
Proximal Tibia	Antegrade	Varus	2 Medial screws
		Valgus	2 lateral screws
		Procurvatum	1–2 Posterior screw(s)
Mid Tibia	Antegrade	Varus	2 Medial screws
		Valgus	2 Lateral screws
		Procurvatum	1–2 Posterior screw(s)

We did not encounter a recurvatum deformity of the femur or tibia, and a distal tibial osteotomy was unnecessary in our experience

Femoral lengthening along the anatomical axis using an ILN leads to lateral mechanical axis deviation, but tibial lengthening along the anatomical axis does not change the mechanical axis since they are parallel